Dynamic thermal response modelling of turbulent fluid flow through pipelines with heat losses

The dynamic thermal behaviour of pipe systems is important in many heating, cooling and process systems and is further complicated where radial heat transfer and the thermal capacity of the pipe are significant. In this study, the ability of three forms of discretized one-dimensional models in prediction of the dynamic thermal response of pipelines considering the longitudinal dispersion of turbulent fluid flow were examined. Furthermore, a model is proposed combining features of plug-flow and discrete stirred tank representations that take into account the thermal capacitance of the pipe material as well as radial heat transfer. This combination enables the proposed model to simultaneously handle the simulation of momentum and energy balance as well as simulation of the longitudinal dispersion in pipelines. The proposed model is further compared to experimental measurements. The results elucidated that the proposed model is not only able to capture the outlet temperature changes due to a step change in the very good agreement against the measurement data but also offers advantages in reduced computational expense

Analysis of non-dimensional numbers of fluid flowing inside tubes of flat plate solar collector

The aim of this paper is to discuss the non-dimensional numbers of fluid flowing through inside the tubes of flat plate solar collectors. Empirically, to abate the cost and energy consumption or to boost up the performance and efficiency of solar collectors; computational simulation plays a vital role. In this study, CFD numerical simulation of aqueous ethylene glycol (60% water + 40%) ethylene glycol fluid flow has been done with ANSYS 15.0. Non-dimensional numbers such as surface Nusselt number, Skin friction coefficient and Prandtl number of fluids have been observed based on empirical and experimental properties. The geometry of design has been prepared using Solidworks software in accordance with the actual experimental model. The analysis revealed that the Nusselt number showed effective convection behavior, the skin friction coefficient was positive while the Prandtl number was large for both properties of aqueous ethylene glycol

Aggregation study of Brownian nanoparticles in convective phenomena

The explanation of abnormal enhancement of transported energy in colloidal nanoparticles in a liquid has sparked much interest in recent years. The complexity comes from the inter-particle phenomenon and cluster formation. The process of nanoparticle aggregation, which is caused by convective phenomena and particle-to-particle interaction energy in a flow, is investigated in this research. Therefore, the probability of collision and cohesion among clusters is modelled, as stated in this research. ANSYS-Fluent 17 CFD tools are employed to implement a new method of nanoparticle aggregation, new essential forces, new heat law and cluster drag coefficient. The importance of the interaction forces is compared to drag force, and essential forces are considered in coupling between nanoparticles and fluid flow. An important parameter is defined for the surface energy density regarding the attractive energy between the double layer and surrounding fluid to capture the cohesion of particles. Particles’ random migration is also presented through their angular and radial displacement. The analyses for interactions show the significance of Brownian motion in both particles’ migration and coupling effects in the fluid. However, nanoparticles are pushed away from walls due to repulsive forces, and Brownian motion is found to be effective mainly on angular displacement around the tube centreline. The attractive energy is found to be dominant when two clusters are at an equal distance. Hence, the cluster formation in convective regions should be taken into account for modelling purposes. A higher concentrated region also occurs midway between the centreline and the heated wall.http://link.springer.com/journal/10973hj2020Mechanical and Aeronautical Engineerin